Check out the Lindsay Wildlife Museum in Walnut Creek, where they do wildlife rehabilitation and have live native animals on exhibit along with other more traditional museum exhibits that kids and adults will enjoy.
John Muir's last home is part of a State Park in Martinez, and Shadelands Ranch museum is in Walnut Creek.
There are also many performing arts venues, including the Chronicle Pavilion in Concord.
The California Delta offers plenty of water activities. (http://www.californiadelt...)
